1. Field of the Invention
This invention relates generally to pressure-sensitive gauges and, more particularly, to a variable-span pressure gauge having means to calibrate the dial pointer over its scale to a wide pressure range, either at the factory or in the field.
2. Description of the Prior Art
As is well known in the art, various problems and difficultes are encountered in providing suitable means for calibrating pressure gauges, particularly gauges that must be adjusted as they are being installed.
There are presently many types of measuring devices to indicate, at any given time, the amount of liquid stored in tanks. However, these units must be provided with an accurate gauge so as to visually indicate the exact amount of liquid stored therein on a constant basis.
Level-indicating devices--particularly those comprising mechanical connections with rods, floats, springs, and other various moving parts--have not been found to be very reliable due to wear, tear and abuse that such mechanical devices must endure.
However, there are some liquid level indicators that do not use mechanical devices, but rely on pressure within their systems. One of the most reliable systems available today is found in U.S. Pat. No. 3,922,915.
This apparatus has been designed to accurately indicate the level of a given liquid in a given size tank or housing. However, it has been found that, because of the various types of liquids and various sizes of the tanks utilized, there has developed a need for an adjustable gauge that can be simply and accurately calibrated to the particular requirements of the liquid and volume of the storage capacity of the tank.
The apparatus as mentioned above, along with the disclosed device hereinafter described, are very readily adapted for use with liquid storage tanks of large vehicles, motor homes, recreational vehicles, boats, etc. As can be understood, these tanks house fuel, water, or other liquids having varying characteristics stored therein; and, thus, the gauges must be capable of being adjustable for individual requirements.